AMPEROMETRIC BATCH INJECTION-ANALYSIS - THEORETICAL ASPECTS OF CURRENT TRANSIENTS AND COMPARISON WITH WALL-JET ELECTRODES IN CONTINUOUS-FLOW

Amperometric detection using the batch injection analysis technique ha s been studied and compared with the current obtained at the wall-jet electrode under similar conditions using the oxidation of potassium fe rrocyanide and the injection of samples of volume 10 to 100 mu L. The form of the current transients has been analyzed and compared with the steady-state response at wail-jet disk electrodes. Good agreement is found at high dispension rate, differences at lower dispension rates b eing ascribed to radial diffusion effects. The importance of tip-elect rode distance and injection volume have been evaluated; it is shown th at the optimum distance is 3 mm and that maximum sensitivity requires a minimum injection volume of 14 mu L. A detection limit of 50 mu M us ing simple amperometric detection is estimated. Implications of these results for the efficient application of amperometric batch injection analysis are discussed.